Payout-glide-flakeoff apparatus for characterizing deodorant and antiperspirant sticks

ABSTRACT

An apparatus and system for characterizing and quantifying certain attributes of antiperspirants and deodorants is provided, such as payout, friction, and flakeoff. The apparatus is capable of reproducibly applying antiperspirants and deodorant to a substrate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. Ser. No.11/971,978, which claims priority to U.S. application Ser. Nos.60/976,527, filed on 1 Oct. 2007 and 61/015,852, filed on 21 Dec. 2007,all of which are incorporated herein by reference.

BACKGROUND

Antiperspirant or deodorant formulations have been developed with arange of different product forms. One of these is a so-called “stick”which is usually a bar of an apparently firm solid material held withina dispensing container and which retains its structural integrity andshape whilst being applied. When a portion of the stick is drawn acrossthe skin surface, a film of the stick composition is transferred to theskin surface. Payout, of a deodorant stick, describes the weight lost toa surface from a typical application of the deodorant stick. Thisattribute and other rheological properties are considerations whendeveloping new stick deodorant products. Therefore, a controlled methodand device for measuring such properties is desirable.

BRIEF SUMMARY

In an embodiment of the present invention, a system for measuring any orall of payout, static friction and kinetic friction is disclosed. Thesystem includes at least one substrate positioned on an XYZtranslational substrate bed. The system includes a sample holder forsupporting a sample, wherein the sample holder and the sample arepositioned perpendicular to the XYZ translational substrate bed. Thesystem further includes a force device placing a predetermined weightonto the sample holder; the predetermined weight determines a contactforce placed by the sample onto the substrate. The system also includesfrictionless bearing table connected to the sample holder and astationary frictionless bearing table positioned parallel to the XYZtranslational substrate bed. The sample holder and the stationaryfrictionless bearing table are connected to a friction sensor. Thesystem also includes a balance for obtaining a first substrate weightbefore movement of the XYZ translational substrate bed and a secondsubstrate weight after movement of the XYZ translational substrate bed.

The system further includes a controller operably coupled to the movingsubstrate bed and the friction sensor and configured to execute amachine readable program code containing executable instructions.

In an embodiment of the present invention, a method for measuring payoutis disclosed. The method comprises positioning a substrate of pre-knownweight on an XYZ translational substrate bed; supporting a sample in asample holder, wherein the sample is perpendicular to the XYZtranslational substrate bed; placing a predetermined weight onto thesample holder so that the sample and substrate form a contact point;first moving the XYZ translational substrate bed at a first sweep speedin a first direction relative to the sample; second moving the XYZtranslational substrate bed at a second sweep speed in a seconddirection relative to the sample; conducting the first moving and thesecond moving for a predetermined number of cycle(s); obtaining a secondsubstrate weight of the substrate after the predetermined number ofcycles; and determining a payout value based on the first substrateweight and the second substrate weight.

In an embodiment of the present invention, a method for measuring one ormore of static friction and kinetic friction is provided. The methodcomprises: positioning a substrate of pre-known weight on an XYZtranslational substrate bed; supporting a sample in a sample holder,wherein the sample is perpendicular to the XYZ translational substratebed; placing a predetermined weight onto the sample holder so that thesample and substrate form a contact point; first moving the XYZtranslational substrate bed at a first sweep speed in a first directionrelative to the sample; second moving the XYZ translational substratebed at a second sweep speed in a second direction relative to thesample; conducting the first moving and the second moving for apredetermined number of cycle(s); during the first moving step and thesecond moving step, measuring one or more friction values at the contactpoint; analyzing one or more friction values generated at the samplecontact point during the first moving step and the second moving step;and determining one or more of a static friction value and a kineticfriction value based on the one or more friction values.

In an embodiment of the present invention, a method for measuringflakeoff is provided. The method comprises: providing a wool sample of apredetermined size; applying an initial weight of a material to the woolsample; attaching a first end of the wool to a stationary holder and asecond end to a movable substrate bed; a stretching step comprisingmoving the movable substrate bed a predetermined distance and returningand then moving it to an opposite direction for the same predetermineddistance and returning for 1 stretch; repeating the stretch step for apredetermined number of stretches; measuring the weight of the woolsample and material after the predetermined number of stretches;determining a weight loss of material from the wool sample as measuredby an amount of material lost from the sample divided by the initialweight of material after the predetermined number of stretches.

In each of the above methods, the methods are conducted on the abovedescribed system.

BRIEF DESCRIPTION OF DRAWINGS

Reference will now be made in detail to embodiments of the presentdisclosure, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

FIG. 1 illustrates an exemplary system to measure payout, staticfriction, kinetic friction, and combinations thereof.

FIG. 2 illustrates an exemplary device to measure payout, staticfriction, kinetic friction, and combinations thereof.

FIG. 3 illustrates an exemplary friction sensor.

FIG. 4 illustrates a model for determining the friction coefficient.

FIG. 5 illustrates an exemplary method using the systems describedherein.

DETAILED DESCRIPTION

As used throughout, ranges are used as a shorthand for describing eachand every value that is within the range. Any value within the range canbe selected as the terminus of the range. In addition, all referencescited herein are hereby incorporated by reference in their entireties.In the event of a conflict in a definition in the present disclosure andthat of a reference, the present disclosure controls.

The present invention provides for systems and methods for measuringpayout, static friction, kinetic friction or combinations thereof. FIG.1 illustrates an exemplary system 100 including a payout friction testerdevice 107, a balance 106, and a controller 101 having a machinereadable program code 108 containing executable instructions. The device107 for measuring payout, static friction, kinetic friction orcombinations thereof can be operably linked to the controller 101through a motor control unit 102. The components of the exemplary system100 illustrated in FIG. 1 are described further below.

FIG. 2 illustrates an exemplary payout friction device 107. Device 107,of system 100, includes: at least one substrate 204 positioned on an XYZtranslational substrate bed 209; a sample holder 201; a force device224; a frictionless bearing table 211; a stationary frictionless bearingtable 212; and a friction sensor 213. Sample holder 201 supports sample206 so that the sample 206 can be positioned perpendicular to the XYZtranslational substrate bed 209 or so that the sample 206 contacts thesubstrate 204 perpendicularly. The sample holder 201 can also supportthe sample 206 such that the sample 206 contacts the substrate 204 at anangle that is less than 90°.

Sample 206 can be any sample that can be analyzed for payout, staticfriction, kinetic friction or combinations thereof. Examples of samplesinclude but are not limited to deodorants (e.g. a deodorant stick),antiperspirants, or combinations thereof. The sample 206 can be securedto the sample holder 201 using a screw 207, such as a knurledthumbscrew, or other means for attachments, such as a clip or othermeans that can secure the sample 206 and assist in orienting itsalignment. The sample clamp 210 can accept deodorant stick canisters 206or other types of sample containers of various sizes and configurations.

Substrate 204 may include materials such as copier grade paper,sandpaper (in differing grades of abrasion) or cloth may be used. Insome embodiments, it is convenient to cut the substrate beforehand inbulk, for example, into approximately 13×25 centimeter strips so thatsingle strips can be clamped in place before testing.

Referring again to FIG. 2, the XYZ translational substrate bed 209functions to move the XYZ translational substrate bed at a first sweepspeed in a first direction and at a second sweep speed in a seconddirection relative to the sample 206. The XYZ translational substratebed 209 is operably coupled to a motorized screw table 202. Themotorized screw table 202 can be driven by an electronic drive unit 217.The electronic drive unit 217 can operate in an automated mode or amanual mode. In the automatic mode, the electronic drive unit 217 caninclude a pulse width modulation speed control so to achieve precisespeed control down to a zero velocity high torque condition. The motor103 can be remotely driven by a velocity signal furnished by thecontroller 101, for example by the controller's analog output channel.This allows precise control over the sweep rate and distance. In themanual mode, an operator manipulates the XYZ translational substrate bed209 using controls of the electronic drive unit 207. An example of anelectronic drive unit 217 is, but not limited to, a Motamatic DriveUnit.

In one embodiment, the XYZ translational substrate bed 209 also includesa heater 222. In some embodiments, the heater 222 is capable of heatingthe substrate 204 to a temperature of about 26.7° C. to about 43.3° C.(about 80° F. to about 110° F.), about 32.2° C. to about 43.3° C. (about90° F. to about 110° F.), about 32.2° C. to about 37.8° C. (about 90° F.to about 100° F.), about 35° C. to about 37.8° C. (about 95° F. to about100° F.), about 36.7° C. to about 37.8° C. (about 98° F. to about 100°F.), 36.7° C. to about 37.2° C. (about 98° F. to about 99° F.), or about37° C. (about 98.6° F.).

Frictionless bearing table 211 is connected to the sample holder 201permitting “frictionless” movement of the sample 206 supported by thesample holder 201. In some embodiments, the frictionless bearing table211 is positioned perpendicular to the XYZ translational substrate bed209. In other embodiments, the frictionless bearing table 211 ispositioned vertically. The frictionless bearing table 211 functions tomaintain an axis of pressure with testing and permits up and downmovement of the sample holder 201. The weight of the sample holder 201can be counter balanced to zero force through counterweight 218 via thepulley tower 220 and cable 219. Additional weight(s) 203 are placed ontop of the sample holder 201 to define the magnitude of contact force(that which presses the sample against the surface).

A stationary frictionless bearing table 212 is positioned parallel tothe XYZ translational substrate bed 209. In some embodiments, thestationary frictionless bearing table 212 is a horizontal frictionlessbearing table. In other embodiments, the stationary frictionless bearingtable 212 is positioned on internal rails supported by a plurality ofball bearings. The stationary frictionless bearing table floor 214 ispart of the base 216 for device 107 and does not move permitting themeasurement of force with respect to a solid reference.

Friction sensor 213 is operably connected to the sample holder 201 andthe stationary frictionless bearing table 212. In one embodiment,friction sensor 213 can be mounted above the XYZ translational bed 209on a bracket secured to the stationary frictionless bearing table floor214. Lateral friction is transmitted to the friction sensor 213 througha linkage 215 coupling arrangement. This linkage 215 can be oriented asclose as practical to the plane of actual friction. Measuring frictionat the sample contact point 223 requires that other friction points inthe machine be eliminated or at least minimized as much as possible. Toaccomplish this, the stationary frictionless bearing table 212 supportsthe upper assembly completely. All of the assembly components can bebound together on a supporting structure 216 (shown as a sideways T inblack). This “rides” as one piece on the stationary frictionless bearingtable 212.

The friction sensor 213 can be any sensor that can be used to detect anddetermine friction. Transferring surface friction to the sensing elementcan be done by a mechanical linkage from the sample holder 201 to thefriction sensor 213. Referring to FIG. 3, the friction sensor 213 isoperably coupled to a linkage 215 including a transmitter bar 301 and alinkage fork 303. Transmitter bar 301 connects registered force at thesample contact point 223 (FIG. 2) from the sample carriage mount 302 tothe linkage fork 303. The linkage fork 303 can be positioned between apair of O-ring dampeners 306 and the pair of O-ring dampeners can bepositioned between a pair of element stops 304. The linkage fork 303 issuspended between two element stops 304 attached to the friction sensorprobe 305. When the linkage fork 303 pushes against a stop its forcecontent is transferred to the friction sensor 213. Physical contact atthe stops is intentionally dampened by rubber “O” rings 306 which assistin smoothing out the elastic ringing that results from abrupt changes inforce direction

Referring again to FIG. 2, device 107 can include a force device 224including a predetermined weight 203, a counter weight 218, a cord 219,a pulley tower 220, and two pulleys 221 a and 221 b. Force device 224functions to place a predetermined weight 203 onto sample holder 201where the predetermined weight 203 determines a contact force placed bythe sample 206 onto the substrate 204. The predetermined weight 203 andthe counter weight 218 can be connected by the cord 219. In someembodiments, the stationary frictionless bearing table 212 supportsforce device 224.

Referring to both FIG. 1 and FIG. 2, system 100 may also include acontroller 101. for monitoring and controlling the desired variables.Any type of controller can be used to operate the system. Installed inthe controller is a multi-functional AID converter card (DAQ) providingthe necessary interface to the system to the various components.Controller 101 is operably coupled to the XYZ translational substratebed 209, the balance 106, and the friction sensor 213 and configured toexecute the machine readable program code 108. Controller 101 isconfigured to execute machine readable program code 108 to performvarious functions. In some embodiments, the functions include, but arenot limited to configuring the balance 106 to obtain the first substrateweight before movement of the XYZ translational substrate bed 209 andthe second substrate weight after movement of the XYZ translationalsubstrate bed 209. Controller 101 also configures the XYZ translationalsubstrate bed 209 to move the XYZ translational substrate bed 209 at afirst sweep speed in a first direction and at a second sweep speed in asecond direction relative to the sample 206. Controller 101 alsoanalyzes one or more friction values, measured by the friction sensor,generated at the sample contact point 223 located between the sample 206and the substrate 204 during movement of the XYZ translational substratebed 209. Controller 101 is further configured to determine a staticfriction value and a kinetic friction value based on the one or morefriction values or determine a payout value based on the first substrateweight and the second substrate weight.

The system of the present invention can also be configured to executemachine readable code containing executable program instructions toperform a variety of functions. In some embodiments, the system isconfigured to perform methods for measuring one or more of thefollowing: payout, static friction and kinetic friction. One embodimentfor measuring one or more of the following: payout, static friction andkinetic friction is illustrated in FIG. 5. In step 501, a firstsubstrate weight of a substrate is obtained. In one embodiment, a freshpiece of substrate 204 is placed into the balance 106 to be weighed. Acontinuous reading from the balance 106 is displayed in the window asthe balance 106 is loaded. Once a stable reading is noted it can be“acquired” by pushing an on screen button labeled “Get weight”. Thesubstrate 204 is then removed from the balance 106 and secured to theXYZ translational bed 209 with clamping plates 208 on the longitudinalsides.

In step 502 the substrate is positioned on an XYZ translationalsubstrate bed after obtaining the first substrate weight. In step 503 asample is supported in a sample holder, wherein the sample isperpendicular to the XYZ translational substrate bed. In step 504 apredetermined weight is placed onto the sample holder so that the sampleand substrate form a contact point.

In step 505 the XYZ translational substrate bed 209 is first moved at afirst sweep speed in a first direction relative to the sample. In step506 the XYZ translational substrate bed is second moved at a secondsweep speed in a second direction relative to the sample. In oneembodiment, controller 101 begins the sweeping process when permissionis given by an operator. In another embodiment, controller 100 beginsthe sweeping process based on an automated process where permission isnot needed but instead the process begins when the sample 206 and thesubstrate 204 are secured. The sweeping steps 505 and 506, are performedby a motorized screw table that is driven by an electronic drive unit.The electronic drive unit can have a pulse width modulation speedcontrol. In some embodiments, the first moving step and the secondmoving step are repeated a predetermined number of times. In someembodiments, the first moving step and the second moving step areperformed 1-50, 1-40, 1-30, 1-20, 1-10, 5-10, 5-15, 5, or 10 times.

The distance moved in the first direction or the second direction by theXYZ translational substrate bed 209, during the sweep steps 505 and 506can be varied. In some embodiments, the distance of the first directionor the second direction is about 5 to about 50 cm, about 5 to about 40cm, about 5 to about 30 cm, about 5 to about 20 cm, about 5 to about 10cm. In some embodiments, distance of the first direction or the seconddirection is about 5, about 10, about 15, about 20, about 25, about 30,about 35, about 40, or about 50 cm.

In step 507 during the first moving step and the second moving step, oneor more friction values at the contact point is measured. In someembodiments, lateral friction can be measured directly as the XYZtranslational substrate bed 209 sweeps in the first and seconddirections. In one embodiment, each response from the friction sensor213 can be displayed in real time at controller 101, as the sweepingcontinues.

In step 508 a second substrate weight of the substrate after the firstmoving step and the second moving step is obtained. When the requestednumber of sweep steps has occurred the computer can re-display the “Getweight” window. The impregnated material, i.e. substrate 204, can beremoved from the lower bed and placed back into the balance 106 to bepost-weighed. Payout is determined from the change in weight of thesubstrate 204.

In step 509 one or more friction values generated at the sample contactpoint during the first moving step and the second moving step isanalyzed. In step 510 a static friction value and a kinetic frictionvalue based on the one or more friction values are determined. In someembodiments the friction values are determined using the formuladescribed herein. In step 511 a payout value based on the firstsubstrate weight and the second substrate weight is determined.

The present invention also provides for determining frictioncoefficients as the substrate and sample pass against one another. Usingthe systems described herein the sample moves or glides across thesubstrate in a pattern that involves acceleration and de-accelerationunlike the previous assumption that the motion occurs with uniformspeed. Therefore, the following model based on Newton's second law wasemployed to calculate the coefficient of friction between the sample andthe substrate. FIG. 4 illustrates a model configuration of the substrateand sample passing against one another where F_(N) is the normal forceapplied to the skin 408, F_(L) is the net lateral force across the skin408, α is the angle between the product 410 and the skin 408 at anygiven time. Based on the configuration displayed in FIG. 4, the frictioncoefficient at any given time can be express as following:

Driving force=F_(L)sin (α)−F_(N)cos (α); Friction Force=μ*[F_(L)cos(α)+F_(N)sin (α)]; Newton's second law: F_(L)sin (α)−F_(N)cos(α)−μ*[F_(L)cos (α)+F_(N)sin (α)]=m*a; μ={F_(L)sin (α)−F_(N)cos(α)−m*a}/[F_(L)cos (α)+F_(N)sin (α)]; where m*a is the inertia of the(carriage+sample) times acceleration (a).

The device 107 can also be used to measure flakeoff. Flakeoff is ameasure of weight loss of material from a sample that has beenstretched. It is a measure of how well a material (such as anantiperspirant/deodorant composition) will remain on a substrate. In oneembodiment, a predetermined amount of material (for example, 0.65±0.03g) to be tested is applied onto a piece of wool (Style #530 fromTestfabrics, Inc.) of a predetermined size (for example, 7.6 cm×15.2 cm(3 in.×6 in.)). The wool is stretched a predetermined distance (forexample 6 cm) and returned and then stretched to the opposite directionfor the same predetermined distance and returned as one stretch. Theweight of the wool and material is measured after a predetermined numberof stretches (for example 50, 150, and/or 450 stretches). The percentweight loss of the material from the wool is recorded as a measure offlake-off. In one embodiment, the results from four samples can beaveraged to give an averaged result. In device 107, one end of the woolis attached to a stationary holder, which is attached to thefrictionless bearing table 211 as replacement of sample holder 201, andthe other end of the wool is attached to substrate bed 209; orientedacross the 15.2 cm length. The wool is thus perpendicular to thesubstrate bed 209. Substrate bed 209 is then moved to stretch the wool.

EXAMPLES Example 1 Payout/Glide On Sample

Payout on a sample is measured using the system described herein. Thesystem holds the deodorant stick flush to the substrate and moves thestick with a set speed over a distance of 100 mm with 500 g of force.The payout program measures the amount of the product applied to acotton substrate after ten strokes, whereas the glide program measuresthe friction to move the stick across the substrate during one stroke.Immediately prior to payout analysis, three sticks of each experimentalstick are cut flat and then the stick surface was is further flattenedor conditioned on the instrument using a speed of 30 mm/sec for twentycycles. In order to determine the payout, the cotton substrate is taredon a balanced and then clamped down on the substrate bed. The stick ispassed over the substrate ten times at a speed of 20 mm/sec, and thenthe substrate is removed and returned to the balance to obtain theweight of the product on the substrate. The payout is measured threetimes on a stick and the average of the three results is calculated. Thefriction coefficient for the first and tenth strokes is recorded.

1. A method for measuring one or more of static friction and kineticfriction comprising: positioning a substrate of pre-known weight on anXYZ translational substrate bed; supporting a sample in a sample holder,wherein the sample is perpendicular to the XYZ translational substratebed; placing a predetermined weight onto the sample holder so that thesample and substrate form a contact point; first moving the XYZtranslational substrate bed at a first sweep speed in a first directionrelative to the sample; second moving the XYZ translational substratebed at a second sweep speed in a second direction relative to thesample; conducting the first moving and the second moving for apredetermined number of cycle(s); during the first moving step and thesecond moving step, measuring one or more friction values at the contactpoint; analyzing one or more friction values generated at the samplecontact point during the first moving step and the second moving step;and determining one or more of a static friction value and a kineticfriction value based on the one or more friction values.
 2. The methodof claim 1 further comprising preconditioning the sample comprisingconducting the method in claim 21 up to the conducting step for 20cycles at a first sweep speed and second sweep speed of 30 mm/s on asubstrate that is then discarded.
 3. The method of claim 1, wherein theXYZ translational substrate bed is heated to a temperature of 37° C. 4.The method of claim 1, wherein the sample comprises an antiperspirant ordeodorant stick.